The story behind these two is that Tracy was a sickly young girl, who would be lucky if she lived past the age of 23. Her parents wanted to quickly marry her off young so she could have a child before she croaked.

Of course, Tracy being the romantic that she is refused to marry someone she didn't even know so she an away. She stowed herself on a ship, not really knowing it was a pirate ship. A couple days at sea and the ship was attacked, reduced to ruins on the water.

Aisu was swimming through those waters at the time and saw her amongst the drowning pirates, feeling sorry for the poor girl.

Ever since that day the two have had a contract, though only Aisu knows about it. Tracy had lost all her memory of her previous life and she drifted up onto shore of a far away town.

Aisu changed the girls appearance and is always just beneath the surface to keep the girl up and running. Aisu only really reveals herself every so often, usually in battles in such >.<

She rarely leaves Tracy's body too.

When she does, Tracy reverts to the way she looks here, though she also goes back to being weak and sickly.